MOSSBAUER-SPECTROSCOPY FOR THE CHARACTERIZATION OF SOILS USED AS CATALYSTS

We have recently reported the use of volcanic ash soil as an iron supported catalyst for the water gas shift reaction, taking into account that one of the characteristics of Chilean soils is their large specific surface area and high iron oxide contents. Here we report the characterization of the soil material which was used as catalysts by means of Mossbauer spectroscopy at room and low temperature. The spectra were dominated by a broad central doublet, which was analyzed into two components attributable to paramagnetic ferric iron. They also show two low intensity magnetically splitted sites, with IS and H(eff) which may be assigned to magnetite or a similar substituted ferrite. No hematite or other common soil iron oxides seem to be present on these samples, but the presence of low crystallinity ferrihydrite may be associated with the central doublets.